Nova Company's total overhead cost at various levels of activity are presented below: Total Machine-Overhead Month April May une July Hours 48,000 38,000 157,960 58,000 210,360 68,000 236,560 Cost $184,160 Assume that the total overhead cost above consists of utilities, supervisory salaries, and maintenance. The breakdown of these costs at the 38,000 machine-hour level of activity is: Utilities (variable) Supervisory salaries (fixed) Maintenance (mixed) Total overhead cost $ 57,000 41,000 59,960 $157,960 Nova Company's management wants to break down the maintenance cost into its variable and fixed cost elements Required: 1. Estimate how much of the $236,560 of overhead cost in July was maintenance cost. (Hint: to do this, it may be helpful to first determine how much of the $236,560 consisted of utilities and supervisory salaries. Think about the behavior of variable and fixed costs.) 2. Using the high-low method, estimate a cost formula for maintenance in the form Y=a +bX. 3. Express the company's total overhead cost in the form Y-a + bX. 4. What total overhead cost would you expect to be incurred at an activity level of 43,000 machine-hours